diff --git a/docs/manual/README.md b/docs/manual/README.md
index fb8e584..3a50876 100644
--- a/docs/manual/README.md
+++ b/docs/manual/README.md
@@ -145,6 +145,8 @@ flag or label the copies agree on, faces and the names on them, and the
 edit if only a copy had one. Where the copies disagree on a flag or a
 label, the one that stays keeps its own and the line says so.
 
+![Two frames with a copy each in a bck folder, checked and proved the same, the copy that stays marked on each](media/duplicates.png)
+
 `Move N copies to trash` does it, one group at a time: each group is merged
 and its spare copies moved together, or not at all. The copies go to the
 trash, not away — select them in the trash view and `Restore` puts them
diff --git a/docs/manual/index.html b/docs/manual/index.html
index 704157c..c6a5b5f 100644
--- a/docs/manual/index.html
+++ b/docs/manual/index.html
@@ -242,6 +242,7 @@ that stays will gain: the highest rating, every keyword and collection, a
 flag or label the copies agree on, faces and the names on them, and the
 edit if only a copy had one. Where the copies disagree on a flag or a
 label, the one that stays keeps its own and the line says so.</p>
+<figure><img loading="lazy" src="media/duplicates.png" alt="Two frames with a copy each in a bck folder, checked and proved the same, the copy that stays marked on each"><figcaption>Two frames with a copy each in a bck folder, checked and proved the same, the copy that stays marked on each</figcaption></figure>
 <p><code>Move N copies to trash</code> does it, one group at a time: each group is merged
 and its spare copies moved together, or not at all. The copies go to the
 trash, not away — select them in the trash view and <code>Restore</code> puts them
diff --git a/docs/manual/media/duplicates.png b/docs/manual/media/duplicates.png
new file mode 100644
index 0000000..3401462
--- /dev/null
+++ b/docs/manual/media/duplicates.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:25bfb3abb610ae0a1e6bacfb6d63efac9cb617a0b4c2bde9cb5cedc2ecac2750
+size 72110
diff --git a/tools/manual/scenes.py b/tools/manual/scenes.py
index 49d7e9e..57dc200 100755
--- a/tools/manual/scenes.py
+++ b/tools/manual/scenes.py
@@ -34,6 +34,7 @@ import fnmatch
 import inspect
 import os
 import re
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -1182,6 +1183,67 @@ def settings():
     pause(1.5)
 
 
+# --- duplicate originals ---------------------------------------------------
+DUPLICATED = [NY_FIRST, '_MG_8394']   # copied into a `bck` folder beside their own
+
+
+def library_file(name):
+    """The path of file `name` in the demo library."""
+    for root, _, files in os.walk(DEMO_LIBRARY):
+        if name in files:
+            return os.path.join(root, name)
+    raise FileNotFoundError(f'{name} is not in {DEMO_LIBRARY}')
+
+
+@scene(media=['duplicates.png'],
+       sources=LIBRARY_SRC + ['ui/dr-ui/ui/duplicates.slint', 'ui/dr-ui/src/duplicates_ui.rs',
+                              'ui/dr-ui/src/duplicates.rs', 'core/dr-catalog/src/duplicates.rs'])
+def duplicates():
+    """The demo library holds no duplicates, so this makes two: copies of two
+    New York frames in a `bck` folder beside theirs, the way a hand-kept
+    backup sits. The app is restarted so its scan finds them, and the row
+    under the trash appears once the sweep has read their capture times. The
+    review is opened from there and checked, and the copies are deleted again
+    before the app is restarted on the library as it was. (The snapshot
+    record.sh restores would remove them too.)"""
+    made = []
+    try:
+        for name in DUPLICATED:
+            src = library_file(f'{name}.CR2')
+            folder = os.path.join(os.path.dirname(src), 'bck')
+            os.makedirs(folder, exist_ok=True)
+            made.append(os.path.join(folder, f'{name}.CR2'))
+            shutil.copy2(src, made[-1])
+        dr.stop()
+        dr.launch([])
+        dr.wait_ready()
+        dr.wait_for('id:grid-scroll', 60)
+        dr.wait_for('Duplicate originals@Text', 300)
+        pause(1)
+        dr.click_on('Duplicate originals@Text')
+        dr.wait_for(f'Check {len(DUPLICATED)} groups@Button', 30)
+        pause(1)
+        dr.click_on(f'Check {len(DUPLICATED)} groups@Button')
+        dr.wait_gone(f'Check {len(DUPLICATED)} groups@Button', 60)
+        pause(3)
+        shot('duplicates')
+        dr.click_on('‹ Back@Button')
+        pause(1)
+    finally:
+        for f in made:
+            if os.path.exists(f):
+                os.remove(f)
+        for f in made:
+            d = os.path.dirname(f)
+            if os.path.isdir(d) and not os.listdir(d):
+                os.rmdir(d)
+    dr.stop()
+    dr.launch([])
+    dr.wait_ready()
+    dr.wait_for('id:grid-scroll', 60)
+    pause(3)
+
+
 # --- running them -----------------------------------------------------------
 def order(names):
     """`names` with their prerequisites, each once, prerequisites first."""